1. Field of the Invention
The present invention relates to a method of converting a digital signal to an extended length binary coded signal which enables to easily finding a change of the signal recorded in a non-rewritable recording medium.
2. Description of the Related Art
Characters and numerals are recorded on a recording medium in a binary form by translating the characters and numerals into predetermined binary coded signals. Conventionally, notwithstanding the fact that the digital signals recorded on the recording medium can be easily changed, there has been no means to detect such an occurrence. A serious problem will arise if no one is aware of the unauthorized change of the data stored in the recording medium.